Rocky Trail Setup

I took the YZ450F to the mountains for the first time this weekend. I left my rebound front and rear at the factory setting, put the compression front and rear all the way to soft, ran 15 psi in the rear and 13 psi in the front tire. The rebound seemed good, the compression was good, but I seemed to deflect off of rocks a lot. Would running a little lower pressure in the front and rear help that, or put my rims in danger?

What are guys that ride rocks a lot running for suspension setup and tire pressure? Your experiences can be a huge help for me.

I definately know now that I need to get a flywheel weight. Only stalled it twice, but I got tired of always have to pull in the clutch while going down technical slow downhills.

Just a thought, maybe if you ride in a rocky evironment a lot it might be worth installing Mousse's rather than your conventional tubes.

I think a lot of what you are noticing is due to the fact that you were running a stiff suspended MX bike in the rocks versus a trail ride like the WR. I notice it too on my YZ, but it doesn't usually bother me enough to worry about it- my suspension is box stock right down to the clicker settings. I'm no expert (in fact I know nothing about suspension tuning) but maybe softening up the rebound will make it more supple in the rocks. I would stick with what you have for tire pressure- that's what I run as well and you run much less risk of a pinched tube with those pressures. I'm interested to see what other replies you get, as I could use the info too.

heavy duty tubes, a little less tire pressure. Reduce the rebound a few clicks at least. Your suspension is "packing up" and not working in the plushest part of the stroke.

Thanks for the input. Keep in coming as I learn from all of it.

I will soften the rebound front and rear a couple clicks, keep the tire pressure as is. I am already running heavy duty tubes with slime in them, so I got that covered. I rode an XR400 on those same trails for years, so I definately know that most of what I am experiencing is the stiffer MX suspension. But the weight difference between the XR and the YZ is absolutely awesome.

The rocks would not bother me if they were ones imbedded in the dirt. But unfortunately I live in an area that has trails covered with medium size rollers (loose rocks). I did a lengthy ride, at decent speed (the guy on the Kawi couldn't stay with me), and did not lay it down, so I guess it's all good.

I'm with you, those big loose rocks all over the place are the worst.

Hey Cowboy - I hate rolling rocks. I sure miss riding the single track trails around North Bend, Oregon when I lived there. Seems all I had to deal with there were tree roots and mud. Some great trails at Beaver Hill, just south of North Bend. I was involved with the off road club that cut and groomed those trails.

I'm way south in OR (2 hours east of Klamath Falls). I grew up riding rocks in Idaho but still hate them- like you say as long as they are anchored I can live it with, but those loose rollers and shale slides are still among my least favorite things to deal with.

heavy duty tubes, a little less tire pressure. Reduce the rebound a few clicks at least. Your suspension is "packing up" and not working in the plushest part of the stroke.

I agree with XRYoda. Since you backed out the compression all the way but left the rebound at the stock setting you are packing up, i.e., because the comp. is soft the fork/shock are compressing really quick but the rebound is not letting it get back 'out' fast enough to be ready for the next hit.

Back out your rebound as far as you can without turning the bike into a pogo stick and you will notice quite a difference.

Also, make sure that you bleed the air out of the forks prior to your ride and later in your ride do it again.

A steering damper will work wonders also!

If you just ride trails, and won't be jumping doubles on a track, consider going to a lighter fork oil, like silkolene 2.5wt, and set the oil level to 4 inches. The level has a big impact on how soft or stiff you want it. You need to remove the springs, and fully compress them when measuring. It is easier to do it with the forks removed, plus you can pump out the old oil that way.

Keep a log on what changes you make, and test it on the same rocky trail. Going this route made my bike much better on the rough stuff, but I noticed I then used more of the full travel of the forks. Still stiff enough at any speed on roads and trails, but too soft on a track.

This has nothing to do with rocks, but I slid my forks up so they protrude 1/4" above the top clamp, and it had a huge improvement on turning ability. Perhaps it's my imagination, but it felt like a whole new bike. Losing 1/4" of travel was worth it.

Regardless of the spring rate you run or oil you use, you can gain a plusher (if that's a word) ride by lowering your fork oil level. This is a simple change that makes a huge difference. Air is compressible, oil is not. By running less oil you effectively make your fork feel softer. I would start by incrementally taking a small volume out and testing at each increment until you are happy with the result. Check your manual for max and min oil levels and stay within in them.

I used to run fork sub tanks on my 426. I would open the valves on the tanks all the way when trail riding. This would effectively increase the air volume of the forks and made them feel way softer. On the opposite side of the spectrum, I would run the sub tank valves closed or nearly so to reduce the air volume and stiffen things up. It was a very quick way to "adjust" the oil level by simply turning a screw.

On the question of fork oil and level, anyone giving advice on the subject would need to know what year 450 you have. It makes a difference. Lowering the oil level has a similar effect in both the '04 and earlier, and the '05 and later models, but the way the oil is measured and the amount of effect lowering the level has is very different between the two forks.

Older models are set to a level, measured with the main tubes and dampers fully compressed, to an oil level between 130-85mm below the top of the tube. If you do mostly trails and rocky stuff, set the level to something around 125-115. The suspension will be less harsh at this level, although lowering the oil from 100 or so will do less to make it plusher than raising it will make it harsher.

The twin chamber fork from '05 on is filled by volume, not by oil level, and is very sensitive to changes in the oil level. They take 350cc per side, and a change of as little as 10cc can often be noticed.

Lighter fork oil will not make the fork plusher because the damping in modern forks works on the basis of pressure regulation. This is deliberately done so that the damping remains consistent as the oil temperature in the fork changes (it can reach 160 degrees F quite easily). The change in oil viscosity from 70 to 140 degrees is 3-5 times the difference from 5 to 10 wt oil at the same temperauture.

Lighter oil may affect bottoming resistance, though, as that is done with fixed orificing, which is affected by oil viscosity.

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